Apparatus for employing low ohmic alloy conductors and method for simplifying current drain data retrieval

ABSTRACT

Apparatus and method for measuring current drain and reporting power consumption using current transformer with primary windings made of low ohmic alloy, enabling the use of the secondary coil to power the sensing and reporting circuits eliminating the power wasted by AC-DC power adaptors used for the current sensors. The saving is substantial as the current sensors will not drain a current when the AC outlets are disconnected from a load or when the load is switched off. The apparatus using low ohmic alloy is extended to the structuring of terminals, including power pins, power sockets and combinations to provide a low ohmic sensing elements in AC plugs, outlets, adaptors and extension cables with multi outlets, dissipating the heat from the sensing elements by the plugs and the larger metal heat dissipation.

FIELD OF THE INVENTION

AC current detecting elements for use in AC outlets and other electricalwiring devices for providing consumption data to users and to a smartgrid of an electric power grid.

BACKGROUND OF THE INVENTION

Many different electrical wiring devices installed into the electricalcircuits of premises, including residences, offices, businesses,factories, public buildings and other buildings require DC powerwhenever control circuits are used for the electrical wiring devices,including circuits used for measuring and communicating powerconsumption.

Electrical wiring devices for controlling LED lights, home automationswitches and relays, controlled power outlets and environment controldevices such as controls for heating, cooling, motorized window shadesand curtains, installed into electrical wall boxes cannot be powered bya separate low voltage DC power lines, nor via a low voltagecommunication line. The electrical and building codes strictly prohibitthe connections of low voltage bus-lines and/or the mingling low voltagewires with wall mounted AC power devices and/or with AC power lines inthe same conduits. It would be similarly against the electrical andsafety rules to connect low voltage communication wires to a currentsensing adaptor, such as a plug-in adaptor for use with AC outlets ofthe present invention. Low voltage bus-lines cannot be directlyconnected to AC wiring devices for reporting to a controller the powerconsumed by an appliance.

This mandates the use of AC power supplies, internally built intoelectrical outlets, switches, relays, dimmers and the like. Such powersupply may use AC transformers or large AC capacitors that are bulky andcostly. Alternatively such small power supply may use power switchingcircuits that are costly and generate noise that must be suppressed bybulky filters.

Analog methods and devices to convert AC power to a low voltage and lowcurrent DC power are simple and generate very little noise, yet analogregulators waste substantial power and the resulting heat must bedissipated. The wasted energy by the analog regulator is far above theactual energy needed to power a control circuit of a given device tooperate, particularly when the control circuits consumes very low powerof few mW, or DC current of few mA and a low DC volt such as 5V, 3.3V or1.8V for its operation.

Such low power consuming control circuits including controls fordimmers, current sensors, relays, power outlets and similar devices,using low power consuming CPU are disclosed in U.S. Pat. Nos. 7,639,907,7,649,727, 7,864,500, 8,041,221, US publications 2010/0278537,2011/0227510, 2011/0311219 and U.S. patent application Ser. Nos.12/963,876 and 13/086,610 are incorporated herein by reference and arereferred to hereafter as the reference patents, publications andapplications.

The power wasted by the power supplies of AC power outlets or of aplugged-in power sensing adaptors incorporating power consumptiondetecting and communicating circuits are significant for the attempts bythe global community to reduce the power consumption by monitoring thepower consumed through power outlets in residences, commercial andindustry use.

The current and power drain measuring and reporting circuit may drainfew mW (milli Watt), but even if the power supply is efficient, theconversion of 120V or 230V AC into 1.8V/1 mA DC power will consume 1 Wor more from the AC power line. Such continuous drain of power by, forexample thirty power outlets and ten switches of a small residence, willwaste energy of 40 W/hour or about 1 KW/day. This will occur even whennot a single appliance or light is operated or even connected to the ACoutlets. The accumulated wasted energy will therefore be over 365KW/year by a small typical residence, such as a two small bedroomapartment. This is a significant consumption that must be resolved. Anew small size low cost AC to DC power supply that does not waste energyis needed.

Common AC current sensors and current measuring elements include ACcurrent transforms and coils for detecting current by induction, verylow ohmic resistors such as 2 mOhm or 10 mOhm, for detecting the currentpassing through them by the level of voltage developing over theresistors terminals and magnetic hall sensors for detecting the magneticflux by a current drain in a conductor.

The induction sensing element, the low ohm resistor element and the hallsensors present structural and assembling method difficulties that arenot simple to solve. This directly affect the needed simplified low costcurrent sensing solution for reporting current consumption by appliancesand other loads, and the accuracy of the very wide ranging unpredictableand randomly consumed power.

The low ohmic resistors used for AC current measurement are typicalstructured resistors, similar to the well known axial resistors orsurface mounted resistors for mounting onto printed circuit boardpatterns. The axial resistors can be soldered onto terminals and othermetal structure by a procedure that may affect the value of such smallvalue resistances ranging for example from 2 mOhm˜20 mOhm.

Further the low ohmic resistors need to be introduced for measuringhigher currents ranging for example, from 5 A to 20 A or even higher,mandating PCB patterns that are wide end thick, or terminals that arelarge sufficiently to carry such heavy current without generating heat.

On the other hand the current transformers for detecting the AC currentby induction are made of larger coils and/or cores, for measuring lowcurrent such as few mA to increase the permeability and the magneticflux for measuring few mA of current drain. This is to enable thecurrent transformers to output signals that are measurable and/or can bedifferentiated from noise levels that are persistent in power lines andthe AC wiring devices of the electrical system.

Therefore the use of prior methods, elements and components results inlarge and bulky units, difficult to introduce into small current sensoradaptors or into AC outlets and switches mounted into electrical wallboxes. The same applies to plug-in current sensors, they must be made tobe esthetically and small in size to be pleasing and not large bulkyobstructive device plugged-in the AC wall socket and onto decorativecovers of such AC outlets.

The hall sensors used for AC current sensing are small and accurate butrequire some 40˜100 mW (5-10V and 8-10 mA) to operate, which contradictthe need to minimize the wasted power by the current sensing circuititself, the power supply and the wasted power by the AC currentdetecting devices. Here too another solution is needed.

SUMMARY OF THE INVENTION

The present invention solution for the structure of the current sensingresistors and current sensing coils or transformer is the introductionof current carrying wires and terminals made of conductive metals withlow resistance such as brass and/or higher resistive metal alloys suchas the known silver/nickel, nickel/copper, phosphor/bronze or similaralloys with low resistance.

The metal alloy in a wire form is to be used as the primary coilwindings of a current transformer, or as a structured terminal processedand manufactured from a metal alloy sheet to enable the mechanicalassembling of the socket terminals of an AC outlet or of a combinationof a socket and plug of a plug-in current sensing adaptor. It can besimilarly applied to the current sensing circuit by using the inherentresistance of a metal alloy structured as a socket or a pin or both forproviding a low ohmic resistance for the detection of the current valuesthrough the measuring of the voltage develop over a portion of thestructure as will be explained later.

The primary winding of a current transformer, onto a core such astoroidal core, C-core, E-core or any other core that can be small insize and provide for adequate winding of the primary and secondary coilsas calculated. It is well known that high internal resistance of atransformer coil is reducing the Q factor of the coil and thetransformer efficiency. Yet a primary coil of a small AC transformer foran AC line of 120V or 230V will be in the range of 100 ohm or more. TheAC transformers are used commonly for reducing the AC line voltage intolow voltage and therefore the number of turns of the primary coilwindings in a commonly used AC transformer will be far larger than thenumber of turns in the secondary winding.

Without going into formulas and calculation details, the basictransformer calculation, i.e. the ratio of the number of turns of theprimary to secondary winding is identical to the input/output voltageratio. For example, a typical AC transformer, such as 120V to 12V, willhave winding ratio of 10:1. In such an example if the number of windingsof the primary coil is 1000, the secondary (the 12V) windings will be100 only. The considerations for current sensing transformers aredifferent.

The current transformers for power lines use a primary coil of very fewwinding or one only. Current transformers use the magnetic fluxgenerated by the current drain through the primary coil, or by a wireextended through the center of a toroidal core, for outputting a lowercurrent developed over a large number of turns in the windings of thesecondary coil. For measuring power consumption through electricalwiring devices in a range of up to 2 KVA it is common for a secondarycoil to consist of 1000˜2000 turns or more, and even that is foroutputting a very small signal level in the micro/milli volt range,corresponding to the current drain by a wire extended through thetransformer core.

The internal resistance of a primary coil wire used in current sensingtransformers is too small. Only non-resistive copper wire with thicknessselected to provide for a specific values of current drain is used. Thevoltages developed, or the voltage drop over the internal resistance ofsuch primary coil is normally ignored because the measured voltage dropis insignificant or even unmeasurable voltage, because it cannot bedifferentiated from the persistent noise in AC lines environment.

Further, there is an insignificant load connected to the secondary coilto induce an increased current in the primary coil and therefore thebasics that apply to power transformers can only partially be applied toa current sensing transformer of the present invention as will beexplained later.

The present invention uses several windings of low resistive wire, madeof metal alloy, that provides higher resistance to the primary coil andthus a measureable voltage drop that can be measured in milli volts, forexample, as high as 100 mV (0.1V) for a current drain of 1 A, and thusthe internal resistance transform the primary coil by itself into anefficient current sensor, with a usable/measureable signal via theprimary coil terminals. At the same time the developing voltage over theprimary coil provide for a step up transformer for powering the currentsensing, the power consumption processing and the communicationcircuits.

The present invention offers thereby a total solution to the powerwaste, first is by generating low AC voltage to equal the needed powerby the sensor circuits with insignificant power loss and the second is,generating zero voltage and a zero power waste when no current ispassing through the primary coil. In other words, zero power is consumedwhen the AC appliance is switched off, or no appliance is connected tothe AC power outlet or to the current sensing adaptor.

The two terminals of the primary coil provide the sensor signal in theform of a voltage drop over the primary coil, caused by the internalresistance of the primary coil made of the metal alloy. The secondarycoil output voltage is the product of the ratio of the small number ofturns of the primary coil and the few hundreds or over a thousandwinding turns of the secondary coil, and the voltage developing over theprimary coil. Vout=Vin×ST/PT, where ST is secondary turns and PT is theprimary turns.

Different considerations are introduced by the present invention, suchas the alloy material, the current drain, the resistances and thicknessof wires, the core size, the maximum magnetic flux and the efficiencylosses at the primary/secondary coils.

Further calculations are the needed magnetic flux to generate thestep-up voltage output by a small number of winding turns, the internalresistance of the primary coil and the minimal power needed by thecircuits.

Because the current sensor circuit consume 6˜10 mW only, the currenttransformer can be reduced to a very small size and provide the mW powerunits needed for the circuits, provide measurable sensor signal outputand offer a perfect power saving solution with no waste, because asstated above, the circuit will operate only when a current is drained bya load. Even then the needed power remains a small fraction of 1 W.

In the following descriptions and the claims the references to an alloywire, or to a low ohmic alloy as referred to a wire used for the primarycoil windings of a current transformer or to a current sensing coil, arenot intended to and do not limit the coil to only alloy wire or to a lowohmic wire. The reference to a primary coil or to a coil, as the casemay be, comprises alloy wire and/or low ohmic alloy wire and/orcombinations of alloy wire and copper wire as well as combinations ofdifferent alloy wires with or without copper wire or to copper wireonly.

The term low ohmic alloy coil and the references to a number of turns ofa coil for providing a given voltage drop and/or flux density cancomprise any combination of wires including alloy wire and/or copperwire. Even though the following description may use the term alloy,alloy wire, low ohmic alloy, or low ohmic wire, the term such as coilmade of low ohmic alloy wire, or made of alloy wire may include coil orprimary coil made of wires comprising alloy and/or copper. Any referenceto number of turns of a coil or of a primary coil may include acombination of a number of alloy wire winding turns and a number ofcopper wire winding turns or a number of copper only turns with a givenlow ohmic value.

Another object of the present invention is to provide a wider range ofcurrent sensing, thereby to enable the measuring of and the reporting ofpower consumption in watt units as low as 1 W and up to, for example, 2KW. Considering the 120V AC, the 1 W will be the current measurement ofapproximately 8 mA while the current drain for 2 KW will be over 16 A.This is a very wide range that cannot be covered by a single currentsensing resistor value. For example a current of 8 mA (1 W/120V) willdevelop a voltage of 80 micro volt over a 10 mOhm resistance and acurrent of 16 A (2 KW/120V) will develop a voltage of 0.16V. The powerdissipation at the 16 A current will cause high heat (0.16V×16 A=2.56 W)and well above an acceptable maximum heat generation and cannot beconsidered for such application.

Accordingly several narrowed ranges are needed, such as 1 W to 50 W, 40W to 300 W, 200 W to 800 W, 600 W to 1.2 KW, 1.0 KW to 1.5 KW and 1.3 KWto 2.5 KW as well as specific narrow band or range such as 2.4 KW 3.0 KWetc. The resistance of the primary coil metal alloy wire is selectedaccording to the measuring range, the current drain and the AC powervoltage applicable. In 120V power line, for the case of 1 W to 50 Wrange the resistance can be 0.2 ohm and the voltage developed over theresistor for a 1 W consumption (8 mA) will be 1.6 mV and for 50 W (416mA) will be 83 mV, dissipating heat of a wasted 35 mW power, and well inthe acceptable level.

Similarly in a 120V power line a current drain of 6.5 A (800 W) willdevelop a voltage drop of 0.013V over 2 mOhm resistance, a current drainof 10 A (1.2 KW) will develop a voltage drop of 0.020 V and power heatof 0.2 W, or 12.5 A (1.5 KW) will develop 0.012V over 1 mOhm (0.15 Wpower dissipation) and 20.83 A (2.5 KW) will develop 0.021V. The powerdissipation of which will be 0.416 W, which is acceptable for the largeroutlet (over 20 A) made for up to 3 KW power consumption. The values andranges presented above are rounded, approximate values for explanationpurposes only and are not the precise consumed power or current drain.

The AC current measurements differ from the measuring of powerconsumption, which must be based on measuring both, the current and thevoltage curves, for resolving the phase shift caused by the appliancesincluding their capacitance and/or motors inductance load values and/orthe AC distortions caused by switching power supplies that are commonlyused in electrical appliances.

Yet, another object of the present invention is to include a rangeselector on the basis of the current drained through the primary coilfor improving the measuring accuracy and the signal to noise ratio byadjusting the current signal amplification. This is achieved byproviding the secondary coil with multi windings that are seriallyconnected, also known as secondary coil taps. Wherein the last windingor tap is designed to output a voltage level capable of powering thecircuit at the lowest specified current drain value, and the firstwinding tap is designed to output a predetermined voltage level when anover current drain is detected. This is for alerting the user that thepower consumed exceeds the measuring limit of the plug-in currentsensing adaptor or the permissible power loading from the AC outlet.

The object of the invention to parcel the current drain measuring rangecan also be attained by a single secondary coil winding that is designedfor the lowest designed current drain level as specified, and to parcelthe measurement by detecting the AC voltage output level and operate themeasurement circuit, including the adjustment of the sensor signalamplification that are explained later. The measurement of the secondaryoutput voltage can also be used to alert or alarm the user to anexcessive current drain passing through the current sensor.

Regardless of the method used, both methods the step method via multisecondary taps and the measurement of the output voltage of a singlesecondary coil are substantially simpler to use and apply, versusattempting to apply amplification control on the basis of the wideranging sensor signals levels including micro and milli Volt signalsdeveloping across the primary coil.

The controller or the CPU of the measurement and communication circuitis preferably programmed to generate and communicate a change in thecurrent status such as on-off or a change in the current drain value. Toavoid a situation when the current is cut off by the user switching offan appliance at random, which promptly cuts the sensor circuit's powersupply, a large low voltage storage capacitor is provided. The storagecapacitor is continuously charged and keeps the charged energy toprovide an extended time duration for the current sensor to communicatea change in the current drain including the switching off the load.

It is preferable that a CPU and the other circuits of the sensor willoperate on a minute current, for example, such as below 1 mA, and that alarge storage capacitor storing a low voltage such as 3.3V, powers thecircuits that communicate and report the current drain, a change in thecurrent drain, a current cut off and/or respond to queries by a systemcontroller. The storage capacitor is charged to full capacity when thecurrent is drained through the current sensor and its designed capacitydepends also on the type of the communications signal employed,including RF, IR and optical signal for propagation data via lightguidesor fiber optic cable, including plastic optical fiber known as POF anddisclosed in the referenced US patents, publications and applications.

The other preferred embodiment of the present invention is the use of aselected metal alloy to form a designed terminal, referred to above as apower plug pin or a socket or a part of a combined pin and socket of aplug-in current sensing adaptor, for enabling the current sensor to be apart of such pin, socket or both. A significant advantage of suchstructure includes the cooling of the sensor by a power plug pin of anAC cable of an appliance, for example, a power cable assembly of an ovencarrying high current to the oven is in physical/thermal contact withthe socket that is formed or structured to be the sensing resistor. Suchcontact enables to disperse or dissipate the developing heat over thesensing resistor to the heavy pin plug including the connected coppercore of the wire of the cable assembly, thereby dissipating and reducingthe heat developed over the resistance structure of the socket terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A˜1C are illustrative images of a toroidal and a C core coils ofthe prior art with access for current carrying wires and a circuitdiagram of the current sensing of the prior art;

FIGS. 2A˜2C show the coils and the circuit diagram of FIGS. 1A˜1Cmodified to include a primary coil of the preferred embodiment of thepresent invention;

FIGS. 2D˜2F show the current transformers of FIGS. 2A˜2C modified by theintroduction of multi secondary windings or multi output taps;

FIG. 3A shows an exploded view of the pin-socket structures with thepin-socket of the live AC is made of alloy conductor structured to forma current sensing resistor of the preferred embodiment of the presentinvention;

FIG. 3B shows the assembly of the current sensor of FIG. 3A;

FIG. 4A shows an exploded view of an AC outlet socket with the live ACsocket is made of alloy conductor and structured to form a currentsensing resistor of the preferred embodiment of the present invention;

FIG. 4B shows the assembly of the AC outlet of FIG. 4A;

FIGS. 5A˜5D are the front and rear exploded views of the pins and a PCBof an AC plug including the metal alloy structured resistor of thepreferred embodiment of the present invention with FIGS. 5B and 5D showthe assembled pins and PCB;

FIGS. 5E˜5F show the overall assembly of the preferred embodiment plugcomprising the pins and the PCB of FIGS. 5A˜5D;

FIG. 6A is a block diagram of the current sensing and power consumptionreporting circuit including the powering of the circuits by the currentsensing transformer of the preferred embodiment of the presentinvention;

FIG. 6B is a block diagram essentially similar to the circuit shown inFIG. 6A with the exception of the powering circuit shown to be a knownpower supply used for AC wiring devices;

FIG. 6C is a block diagram of the other preferred embodiment of thepresent invention, essentially combining the circuit of FIGS. 6A and 6Band include a current sensor made of metal alloy and formed into an ACplug or socket or both;

FIG. 7A is a block diagram similar to FIG. 6A expanded to include arange selector through the multi secondary coil taps of yet anotherpreferred embodiment of the present invention;

FIG. 7B is a block diagram similar to FIG. 6C expanded to provide acombined circuit for current sensing of a plurality of AC outlets andother AC wiring devices;

FIG. 8 is a graph showing the AC current and voltage phase shift waveforms and the timed measuring positions for calculating the actual powerconsumption.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1A shows a well known typical toroidal coil assembly 1A comprisinga core 5A and windings 6A for sensing the AC current drained by theshown wire 10 extended through the center of the core 5A. The sensorcoil output its current signal to a processor (not shown).

FIG. 1B shows another well known C core coil assembly 1B comprising theC core 5B with an access or a window and windings 6B for sensing an ACcurrent drained by the shown wire 10 extended through the window foroutputting a sensor signal to a processor (not shown).

FIG. 1C shows a principal circuit diagram 1C of a core 5C and a coil 6Crepresenting the coils 5A or 5B and the core 6A or 6B respectively, forsensing the AC current drained through the wire 10 and outputtingcurrent sensing signal from the coil 6C. The circuit is shown in FIG. 6Band is explained later.

FIG. 2A shows a current sensor 2A which is a modified current sensor 1Awherein the current carrying wire 10 is replaced by a primary coil 11A.The primary coil is made of an alloy wire having a low ohmic resistanceof several milli ohm for developing a voltage drop over the primarycoil, corresponding to the current drained through the coil 11A. Thevoltage drop is used by the processing circuits to calculate the powerconsumption by a load or an appliance such as lights or a refrigerator,or an air conditioner and/or any other electrical appliance. The core 5Ais a toroidal core identical with the core 5A of the current sensor 1A,the secondary coil 12A however is modified to output an AC voltage and asufficient current for powering the processing and communicationcircuits shown in FIG. 6A, which will be explained later.

FIG. 2B shows a modified current sensor 2B, similar to the currentsensor 1B shown in FIG. 1B, it uses the core 5B and structure, similarto the core 5A of the sensor 1B, replacing the wire 10 of the sensor 2Bwith a primary coil 11B that is made, similar to the primary coil 11Aand refer to above, from a low ohmic alloy wire for developing a voltagedrop proportional to the current drain through the primary coil 11B. Thesecondary coil 12B, similar to the secondary coil 12A, is designed tooutput an AC voltage with a sufficient current for powering theprocessing and communication circuits shown in FIG. 6A.

FIG. 2C shows the circuit diagram 2C of the current sensors 2A and 2Bshowing a core 5C, a primary coil 11C and secondary coil 12Crepresenting both current sensors 2A and 2B, the circuit 2C is shownalso in FIG. 6A that is explained later.

FIGS. 2D, 2E and 2F show current sensors similar to the current sensorsshown in FIGS. 2A, 2B and 2C with the exception of the secondary coils,that are shown here as multi windings or a secondary coil with multitaps, for providing range selection and control that is shown in FIG. 7Aand will be explained later. Otherwise the structure of the core and theprimary coils are identical with the cores and the primary shown inFIGS. 2A, 2B and 2C.

FIG. 3A shows an exploded view of the elements of a plug-in currentsensing adaptor 20 for communicating current consumption comprising acombination 22 of a socket 22S and a plug pin 22P for the neutral powerterminal, a combination 23 of a ground socket 23S and a plug 23P and acombination 21 of a socket 21S a plug 21P and a structured resistor 21R.The combination 21 is made of a low ohmic alloy such as brass,copper-nickel or silver-nickel or phosphor-bronze material or any otherlow ohmic metal alloy.

The resistor portion 21R is calculated to be a low ohmic resistorstructure, including two formed integral terminals 21R-1 and 21R-2 thatare solder terminals for supporting the printed circuit board 24. ThePCB comprising the current and power consumption processing andcommunication circuits including the optical transceiver 25 forcommunication optical signals via a lightguide of fiber optic cable andthe RF antenna 54 shown in FIGS. 6A˜6C and 7A, and is structured in aform of a printed pattern onto the PCB board 24. The lightguide and thefiber optic cable and the optical transceiver are disclosed in thereference US patents, publication and applications.

FIG. 3B shows the mechanical assembly including the PCB 24 mounted ontothe pin-socket combination 21, the neutral AC pin-socket combination 22and the ground pin-socket 23 of the plug-in current sensor adaptor 20.The ground terminal has no function in the current drain detectionand/or the current signal processing. FIG. 3B introduces the groundterminal to illustrate that the current sensing adaptor 20 is fullycompliant with the electrical rules, codes and regulations governingground connections.

The plug pins and sockets of the current sensing adaptor 20 are shown tobe the US standards, but any other standard including the Great Britainstandards, any of the different European standards, Australian standardsor any other country standards for a structured pins and sockets orterminals can be complied with to provide current sensing adaptors thatare in compliance with the dimensions, structure, codes and regulationsgoverning electrical wiring devices. Similarly the plug-in currentsensing adaptor 20 can be structured without the ground pin plug andsocket 23 and its case or outer package 29 can be modified to fit 2 pinwall mounted AC outlet, without the ground terminal.

FIG. 4A is an exploded view of a wall mounted AC outlet socket terminalsincluding the live AC terminal 31 made of a low ohmic resistance alloyand comprising the socket 31S, the terminal 31T for wire connection, thestructured current sensing resistor 31R and the PCB mounting terminal31R-1 and 31R-2. The shown PCB 34 is similar to the PCB 21 shown inFIGS. 3A˜3B and so is the structured resistor 31R with its solderterminals 31R-1 and 31R-2. They are shown similar to the structuredresistor 21R.

The structured resistors 21R and 31R can be structured in endlessshapes, thicknesses, width, length, variations of which can be used tochange the resistance values. The construction of the terminals, pinsand sockets can be designed to meet cost targets, the terminals can beformed from a single thick cut sheet or a bended into multi-layer thinsheet, or punched, pressed or use riveted pieces of copper and low ohmicmetal alloy combinations.

It is a cost effective solution to provide for different current drainranges, when the only change between the AC outlets incorporatingcurrent sensor will be a change of the live AC terminal, structured fora given range of current drain or power consumption, along with a changein the AC outlet marking and/or the introduction of color codes to theAC outlets. This will identify the AC outlets that should be used ormated with an AC plug having identical markings or color codes.

For the above reason the structured resistors 21R and 31R are shown isto introduce a common shaped structure of a similar structure but, asreferred to above, there are endless possibilities for the design ofterminals, sockets and plugs to be structured, manufactured andassembled to provide a selected current sensing resistance. An examplefor such design is shown in FIGS. 5A˜5F.

The other terminals of the wall mounted power outlet including theneutral terminal socket 32 and the ground terminal socket 33 are typicalterminals used in power outlets shown as standard US power outlet, butcan apply to power outlets of any country or region.

All other consideration for the PCB 34 including the communicationcircuit and the optical transceiver 25 are similar to the PCB 24referred to in FIGS. 3A and 3B. The obvious change is seen by theremoval of the plug pins 21P, 22P and 23P and replacing them with theshown screw terminals 31T, 32T and 33T. The ground terminal 33T and theground socket 33S have no role in the circuits and structures referredto the present invention and they are shown to be compliant withgrounding codes and rules. Power outlets with or without the groundterminals can be used by structuring a single or multiple AC poweroutlets with two terminal sockets per each outlet, the neutral and thelive AC.

Shown in FIG. 4B is a single AC outlet assembly 30 combining the entireset-up of the exploded view shown in FIG. 4A, however such poweroutlets, wall mounted or other types, such as outlet adaptors or outletscombined with cable and plug assembly, having plurality or multiple ofAC sockets that are in fact plurality of power outlets and each can bestructured similar to the preferred embodiment, including the resistor31R or other structure for providing a low ohmic sensing resistors tothe live AC terminal. In many such multi AC outlets the neutral terminalsockets and the live AC terminal sockets are combined into a singlestructured bar, each bar is connected to a single neutral AC wire and asingle live AC wire respectively for providing AC power to all theplurality of the AC outlet.

In such a set-up each of the live AC terminal sockets must be structuredto include a low ohmic resistor such as the shown 31R or any otherstructure for each of the live AC terminal sockets. Same apply to powercable assemblies with multi power sockets and to the AC adaptors knownas plug-in multi outlets adaptors. The PCB assembly for multi AC outletscan be a combined assembly with a single CPU or a single signalprocessor for all the plurality of sockets, including the reporting ofthe power consumption by each live AC socket terminal individually. Thecombined circuit shown in FIG. 7B will be explained later.

In the following description and the claims the term CPU (CentralProcessing Unit) refers to a CPU or to a DSP (Digital Signal Processor)or the any other signal processor be it analog to digital, digital toanalog and any combinations of signal processing devices, ICs, andcircuit packages.

FIGS. 5A and 5C are the front and rear side of an exploded views showingthe structure of power pin terminals 41P, 42P and 43P, which are thelive AC pin, the neutral AC pin, and the ground pin respectively. Thepins are similar to the pins 21P, 22P and 23P shown in FIG. 3A but thepins 41P and 42P are structured differently for mounting onto a rear PCB44 and the ground pin 43P is structured for direct connection to aground wire.

The resistor 41R is structured as a part of the pin 41P, but because ofspacing limitation and the total size of the plug 40, the resistor 41Rwas formed in a shape of vertically elongated square wave cuts toprovide the length needed to achieve the designed low ohmic resistancefor a defined current drain through the AC plug 40.

The shown square wave shaped resistance is an example of the endlesspossibilities of designed shapes, thicknesses, width, length and themetal alloy selection for introducing a defined resistance, designed formeasuring the current drained through a structured terminal, pin orsocket and a combination thereof. The structured pins can be designedwith solder pins, solder terminals holes, threaded holes and otherstructured shapes to install and connect the resistance portion to thePCB and the whole plug accurately and safely.

FIGS. 5B and 5D show the assembly of the pins 41P and 42P including theoptical transceiver 45 onto the PCB 44. The ground pin 43P is not shownassembled or connected to the PCB, it has no specific function toprovide, even though it can be used for shielding the circuit fromnoise. The ground wire 46G shown in FIGS. 5E and 5F is connected to theground pin 43P. Not shown is the RF antenna 54 of FIGS. 6A˜6C and 7A˜7Bfor communicating two way RF signals, because such antenna is providedin the form of a small pattern onto the PCB itself and the PCB 44therefore includes the antenna 54.

FIGS. 5E and 5F illustrate the molded plug 40, assembled and connectedto the power cable 46 with its live AC wire connected to the loadterminal 41L which is shown as a solder terminal of the resistor 41R,for connecting an appliance (not shown) to the other end of the powercable 46. This completes the introduction of the load resistor 41R inseries between the AC live line via pin 41P and the appliance via thecable 46. The neutral wire 46N of the cable 46 is connected directly tothe terminal 42P and as referred to above, the ground wire 46G isconnected directly to the ground pin 43P and not to the PCB.

The shown optical transceiver communicates optical signals to alightguide or fiber optical cable, which is disclosed in the referencedUS patents, publications and applications as accessed via an opticalaccess or an optical port of an AC outlet for propagating datapertaining current drain, power consumption and the load or theappliance particulars. The other way of the two way communicationsinclude inquiries by the system controller and commands for operatingthe appliance.

FIG. 6A shows a block diagram of the current sensor circuits includingthe power consumption reporting circuit and the communication circuitsof the preferred embodiment of the present invention, using the currenttransformer shown in FIGS. 2A˜2C for powering the current sensorcircuits. The circuits including the CPU or analog/digital processor 50,the current signal amplifier 51 and the power supply regulator 57 arethe basic circuits for the current sensing and processing including themeasuring of the power consumed by a load 58. The load is shown as anohmic RL, an inductance LL and/or capacitance CL loads and combinationsthereof.

The sensing element is the current transformer T1 with its primary coilP consisting of several windings made of a low resistance alloy wirewith its thickness selected for a given range of current drain by a load58. The load is connected between the neutral AC terminal 59 and theload terminal 60 and through the primary coil P of T1 to the live ACterminal 61. The communication circuits include the two way buffer 52the optical transceiver 56 and the RF transceiver 53.

The current transformer T1 is differently structured from the well knowncurrent transformers which commonly include a secondary coil woundedover a toroidal core such as shown in FIG. 1A, for providing a passageor a window for current carrying wire 10 through the center of the core.The current flow through the straight passing wire 10 shown, consideredas a single turn, generates magnetic flux that produces a current in thesecondary coil S. The current is proportional to the winding turns ratioand will develop a signal voltage output over a load connected to thesecondary coil terminals.

The voltage drop over the wire 10 shown in FIGS. 1A˜1C is unmesurablebecause power carrying wires are selected to provide minimum ohmic lossover the power propagating distance. The length of the wire passing thecore is few milli meters only. A voltage drop over a micro ohmresistance of a short copper wire is too small and will not change inany significant way if the copper wire is wound onto the core as shownin FIGS. 2A˜2C. The voltage drop over the primary coil 11A˜11C will beinsignificant and far too small to measure. The electrical noise and humpersisting in power lines environment prevent the measuring of microvolts levels, and/or the use of a low milli volt signal reliably.

The secondary current will increase by the windings of the primary coil.The passing straight “single wound” wire provides limited magnetic fluxand the several windings increase the flux substantially within the corelimitation, such as the core permeability and size.

Further, the commonly used current transformers are specifically madefor introduction onto power lines without intersecting the AC wires.This is a concept developed for measuring current in the very highvoltage power lines for metering the power consumption, and the metersare away from the power lines and must be totally insulated from thehigh voltage.

The limitations for the electrical wiring devices, be it in buildings,including factories, warehouses, schools, public places, shops,residences, businesses and others, are that the strict electrical andbuildings codes and rules prohibit the connections and/or the minglingof low voltages signaling and/or low voltage power with the electricalwiring devices and/or the electrical wiring.

This mandates the use of RF or optical communications, be it visuallight or IR in air or via optical cables such as lightguide, (lightguideis a trademark by Toray Industry of Japan for its plastic optical fiber,known as POF) or fiber optic cable. Yet the RF and the opticalcommunications including the current signal processing circuits must bepowered by a low volt and low current power source and this is a hurdlethat must be overcome.

The practicality of the electrical wiring devices is their size withinthe electrical wall boxes. The introduction of current sensors intoelectrical outlets and light switches presents a size problem. It isdifficult to introduce, even a small power transformer to eachelectrical wiring device including power outlets.

Moreover, it is costly and wasteful to introduce individual power supplybe it switching power supply, or analog power supply using a transformeror high voltage AC grade capacitor, for feeding the DC power supply witha reduced AC voltage. It makes no sense particularly when the purposefor the consumption reporting and control is a reduction in the powerconsumption.

Using the present available techniques for a small size power supplieswill end up with noisier electrical environment caused by the as manyswitching power supplies and/or heated wiring devices by the largerelatively power waste resulting from the analog power regulation. Thepower consumption by the electrical wiring devices will be continuouseven though most of the electrical wiring devices are not in use most ofthe day or at all.

Many outlets remain unused in buildings, homes, businesses and otherpremises. Considering that the average number of electrical wiringdevices in premises are well above 60 per building's unit, theintroduction of small power supplies to the 60 devices in millions ofpremises, with each power supply consumes as little as 1 W/hr. or 24W/per day, for 365 days/year, will end up with over 500 KW/hr. annuallyper residence and with Gigawatts power waste for a city or a state. Thepresent invention, changing the way current transformer is designed andused, fully eliminates the wasted power by the unused electrical wiringdevices.

The primary coil P of T1 is made of a low ohmic alloy wire such ascopper-nickel, silver-nickel, phosphor-bronze or a brass alloy, all areconductors with low resistance that can be made in different wirethicknesses for current up to 30 A or more wound onto a small sizeferrite or metal based transformer core, fit for installation into wallboxes of the electrical wiring devices.

The use of a selected low ohmic resistance wire ranging from 0.1 ohm˜0.2mOhm, for sensing current ranging from 8 mA (approx. 1 W in the USA or 2W in Europe) and up to 30 A (approx. 3.6 KW in USA or 6.9 KW in Europe).Current sensors for loads of 3 KW and over are not commonly used inresidences and can be of a larger physical size. The shown values are toenhance the level and the extent to which a small current transformer ofthe present invention can be used.

The voltage drop over a 1 ohm resistance by a 1 W consuming appliancedraining a current of approximately 8 mA through a 3 turns primary coil,will be 8 mV.

The VCC shown in FIG. 6A has to provide, for example, 3.3V/2 mA foroperating the processing circuits shown in FIG. 6A. For the 3.3V/2 mA, asecondary coil made of 0.07 mm diameter wire (adequate for up to 6 mA)and a given number of winding turns to output, for example, 5˜6 VAC toprovide for a regulated 3.3 VDC by the voltage regulator 57.

If the ratio of the primary to secondary winding turns needs to be, forexample, 1:750 it is preferable to add some turns and make a ratio suchas 1:850 to provide for core losses, secondary winding losses (some 50Ω)by the 2500 winding turns (0.1V loss at 2 mA) and other knowntransformer losses. It is clear that a load consuming a low 1 W powercan generate the 12 mWAC for the DC power needed to operate the currentsensor shown in FIG. 6A.

On the other end, a 1 ohm resistance and the 2500 secondary turns willbe too large even for a 10 W load, as the current drain will be 80 mAraising the voltage drop to 80 mV. Even though the heat dissipation overthe primary coil (0.08 A×0.08V) is an acceptable power waste of 6.4 mW,the voltage developing over the secondary coil (0.08V×850 turns ratio)is in the range of 30 VAC (loaded) and it is too high for the 3.3Vanalog regulator 57 and a lower secondary output voltage is needed. Thesolution shown in FIG. 7A provides cascading secondary coils or taps tothe secondary coil S and a controlled output selector.

FIG. 7A will be discussed later, but it is clear that the introductionof a resistance in the magnitude of 1 ohm to the primary coil is toolarge and a smaller resistance is needed. With smaller resistance thepowering circuit shown in FIG. 6A will be limited to a higher currentrange, particularly when a very small power consumption in the range of1 W or less and up to 20 W, or 60 W or even up to 100 W. For small powerconsumption sensors the DC power circuit of FIGS. 6B and 6C showing theother preferred embodiments of the present invention will preferablyapply.

FIG. 6B is a block diagram with circuit essentially similar to the blockdiagram of FIG. 6A with the exception of the VCC power supply source,and the use of the secondary coil for outputting current sensing signalinstead of the AC power source for the VCC. The VCC power source in FIG.6B is fed via the protection resistor R2, the capacitor C3 and the diodeD2 to the input or terminal of the DC regulator 57.

The regulator 57 shown is the well known analog voltage regulator ICavailable by many IC manufacturers at very low cost. The shown regulatorinput circuit includes the filter capacitor C1 for providing low rippledDC input to the regulator and a zener diode ZD1 for protecting theregulator from voltage surges, commonly affecting the electricalsystems. The output of the regulator includes a storage capacitor C2 formaintaining sufficient charge to power the current sensor circuits whenpower is randomly cut, in order to report such random cut to the systemcontroller.

The live AC line is shown connected to the ground which is also thenegative line of the VCC. The VCC shown is, for example, as a positive3.3V, but can be 5V or 1.8V or any voltage commonly applied to a CPU andother ICs, including communication ICs, such as shown in FIGS. 6A˜6C and7A˜7B.

As the live AC is connected to the negative pole of the DC supply, thepower feed into the input terminal of the voltage regulator 57 isconnected to and fed from the neutral AC line to the rectifying diode D2via the series capacitor C3, an AC grade capacitor, and depending on thepower line voltages, may range from, 0.1 micro farad for the 230/240 VAC(EU, UK) and up to 0.18˜0.22 micro farad for 100/120 VA (Japan/US) alsoconsidering the power frequency 50 Hz or 60 Hz respectively.

The capacitor C3 rated at 275 VAC is well known and is approved by allknown standard approving entities such as UL, VDE, JIS and BS for use inelectrical power circuits. The resistor R2 between the capacitor C3 andthe neutral AC line is a protection resistor to prevent surges and/ormay be a self-destructive resistor to prevent fire in the remote eventthat a short circuit or heavy leakage will occur.

The current transformer TB is similar to the transformer shown in FIGS.1A˜1C, but the primary or the straight wire or a bar 10 is made of lowohmic alloy to increase the voltage drop over the primary terminals.Moreover it can be coiled around the core, similar to the primary11A˜11C shown in FIGS. 2A˜2C to increase the magnetic flux and signallevel of the secondary SB coil which is needed to overcome thepersisting electrical noise. This is to increase the very low outputsignal levels generated by the small current transformer when a lowcurrent in a range of 1 mA˜500 mA is drained by a load through theprimary wire or coil 10.

The signal amplifier 51 is the well known linear amplifier or dualamplifiers IC, connected in series for amplifying the secondary outputsignal. The amplifier 51, combining two amplifiers also known asoperational amp. or op. amp., with each amp is set to amplify by, forexample, up to a factor of 100 and the two in the series can thereforeprovide up to 10,000 amplification factor. The linear amplifying of thesignals generated by the 1˜500 mA drain will be well within the linearrange of the amplifier 51.

The CPU (Central Processing Unit) or analog/digital processor 50hereafter referred to as CPU includes analog to digital and digital toanalog converter ports, digital ports and analog ports.

The CPU 51 is a commonly available CPU, such as 8 bit or 16 bit lowcost, low power consuming processor including a memory. The CPU operateson 1.8V or 3.3V, with an operating current such as less than 1 mA and asleeping current of few micro Amperes.

The amplified current signal is fed from the amplifier 51 to the portI/OC and based on the amplification control status and the datapertaining to the converted analog current signal to digital, the CPU,is programmed to adjust via the I/O A port the amplification factor ofthe amplifier 51 to obtain the optimum amplification as programmed,commensurate with the received signal to be in mid or most linear rangeof the sensor specified range.

As shown in FIGS. 6A˜6C and 7A˜7B and referred to above, the load 58 isnot a pure ohmic or a resistance load, it may be a motor and/or acapacitor and/or a switching power supply commonly used with electricalappliances including PCs. Non ohmic loads cause a shift in phase betweenthe voltage curve and the current curve and/or distort the curve by highpower digital switching power loads. FIG. 8 shows two sinusoidal curves,the voltage curve 80˜86 and the current curve 90˜96, which are shiftedby a random angle, caused by an unknown RL, LL, and CL load.

The voltage curve 90˜96 is curve of a reference voltage fed to the I/OVof the CPU from the neutral AC terminal 62 via a large ohmic divider R1and R3, with R1 value is in a range such as 0.5˜1.0 Mohm and R3 value isfew Kohm, to provide an optimum reference signal level representing thepower line voltage, the 120V/60 Hz of the US or the 230V/50 Hz of theEuropean power line. The current curve 90˜96 is the amplified currentsignal and an accurate reference of the current drain value.

A zero crossing 80 of the reference voltage curve is the start positionor point in time for the processing of power consumption reading. Thecurrent phase shift is evident from the deviation of the zero crossingof the current curve.

The zero crossing 80 shown is the cross from negative to positive, atthat same time, the start position time 90, the current curve is shownto be close to the peak of the negative curve, or at a phase shift ofmore than 90°.

The processing shown in FIG. 8 is the measuring of the five referencecycles 81˜85 and the phase shifted five current cycles 91˜95. Themeasuring positions or points in time are shown in FIG. 8 as ten pointsrandomly spread over the voltage curve as 81-1, 82-1, 83-2, 84-3 and85-4 for the voltage points of time, with the exact point of times overthe current curve shown as 92-4, 93-5, 94-6 and 95-8. The end ofprocessing positions or point of times are shown as 86 and 96. The showntime interval is 2 mSec for 50 Hz and 16.6 mSec for 60 Hz. The verticallines divide one cycle into ten points of time, therefore the intervalbetween each point of time is the time duration of one cycle divided by10.

The time interval or the number of measure points during one cycle (Hz)directly relates to the accuracy of the measurement, same applies to thenumber of measured AC cycles in one measuring round. Both are a decisionto be made, in which higher accuracy require more measured AC cycles(Hz) in one measuring round and a decrease in time intervals or anincrease in the number of measuring point.

The power consumption is the product of a calculated sinusoidal V×Agraphs created on the basis of the measured values at each point of timesimultaneously and summed up per each cycle on the basis of the voltagereferenced timing. The shown five cycles 81˜85 in FIG. 8 are an exampleof one round of measurement repeated, for example, every two seconds.When a calculation round is programmed to be carried every two secondsthe total of five measured cycles will be multiplied by a factor of 20for 50 Hz and 120 for 60 Hz (50:5/sec.×2 sec.) or (60:5/sec.×2 sec.).This will represent the power consumed in two seconds.

By the above it should be obvious that the power consumption calculationby the current sensors of the present invention can be simplified andperformed by a low cost Central Processing Unit (CPU) or ananalog/digital processor both are available from many IC manufacturers.It should be also obvious that the current sensor of the presentinvention can be made small in size, fit into AC plugs, plug-in currentsensors, AC outlets and other electrical wiring devices and provideaccurate, practical and low cost solution to the power consumptionreporting.

The calculated power consumed values are stored and updated in thememory included in the CPU for reporting as programmed to a controller.The calculated power consumption value is converted into a predefinedprogrammed protocol that includes particulars of the load or applianceand the location of load and/or of the AC outlet. The stored and updateddata in the memory are the coded protocols.

The referenced patents, publications and application, particularlyapplication Ser. No. 13/086,610 discloses the coding of powerconsumption protocols and the signal structure of the protocolreporting. The command structure is designed to be short commandcomprising five bytes only that include all the necessary data forreporting power consumption, the load particulars and its location.

The short command is necessary particularly when the load is switchedoff thereby cutting the power to the sensor circuits, so as to minimizethe charged storage capacitor C2 drain, when the current sensor reportsthe load new status or “a load switch off” protocol. This is importantas the optical LED transmitter drains several mA such as 5˜6 mA and astorage capacitor to cover responses for several communications, such asresponding to inquiry from a controller when the power is cut (no loadcurrent) will require very big capacitance and an increased size.

The RF transmitter output measured commonly in micro watt units, doesnot consume much power, however, it is preferable to minimize the lengthof the reporting protocols. The shown two transceivers the RF 53 and theoptical 56 are not needed in pairs. Systems operating on RF may notinclude the optical transceiver 56 and systems operating through opticalnetwork may not include the RF transceiver 53. Regardless it is possibleto include both in the circuit and operate wireless and optical networkin parallel.

The two way buffer 52 is a well known amplifier-buffer, available insmall surface mounted IC packages from many semiconductor manufacturers.Its purpose is to interface the signals and their levels and feed thetwo way signals between the transceivers 53 and 56 to the CPU 50 I/O Tand I/O R ports. Depending on the selected CPU and the analog/digitalprocessor 50 there are many such devices that include I/O ports thatrequire no additional buffer as they can be programmed to output andreceive varying signals commensurate with the signal exchanged betweenthe CPU and the transceivers. For such devices the two way buffer 52 isnot needed and is not used.

The block diagram of FIG. 6B is similar to the block diagram and thecircuit of FIG. 6A with the exception of the power supply and thesensing transformer TB. The transformer TB as explained above uses thelow ohmic wire for its primary coil or straight through wire 10 andapplies its secondary SB output signal generated by the TB in responseto current drain via the primary coil or wire 10.

The block diagram of FIG. 6B is a preferred embodiment for low currentconsumption load such as up to 100 W for use in small plug-in currentsensor adaptor similar to the shown in FIG. 3B.

FIG. 6C is literally identical block diagram with FIG. 6B with theexception of the current transformer 6B that is replaced by thestructured terminal RS made of low ohmic alloy for providing voltagedrop that is used for measuring the current drain through a terminalsuch as 21, 31 or 41 of FIGS. 3A, 4A and 5A. All other circuits areidentical with the circuit of FIGS. 6A and 6B. The power supply circuitis identical with the power supply of FIG. 6B explained above.

FIG. 6C is provided for higher currents and higher power consumptionreporting, as the structured terminal and the selection of alloymaterial and thickness make it feasible to drain via the terminalcurrents of 30 A and over. The heat remains well within the well below 1W by the power waste over the low ohmic resistor, and is dissipated viathe plugs contacts. It is clear that the use of low ohmic alloys incurrent sensing devices and components provide whole new prospects tothe introduction of low cost, reliable and easy to handle powerconsumption reporting devices.

FIG. 7A shows the block diagram of FIG. 6A modified to include thecurrent transformer T11 with multi n winding or n taps for enabling toextend the current sensing range, as explained above from low currentdrain of few mA and up to several amperes. The taps A, B, C and n areshown to feed their rectified output, rectified by the diodes D1, 2, 3and n and filtered by the capacitors C11˜n to I/O ports I/O 1˜I/O n ofthe CPU 50A with expanded I/O ports and to a selector 63. The outputselector 63 can be a low cost multi input analog multiplexer known asanalog switch and available from many IC manufacturers, such as Maxim,JRC, Texas Instrument and many more.

Even though such multiplexers are designed for signals selections, thesignals are specified to be 18V and over with current of 25 mA and over,well above the few mA DC fed from each tap of the secondary coil S, withvoltages well below the 18V or the 25V that are common for such analogswitch or multiplexer 63. The I/O S of the CPU control the multiplexervia its control terminal to select the lowest voltage that the CPU hasmeasured to be above a given level as programmed by connecting theidentified output A, B, C or n through the multiplexer output terminalto the regulator input.

The default setting for the multiplexer control is tap A that outputsthe highest voltage, it is the output or tap designed to providesufficient power for the lowest current drain via the primary P. Themid-range current is designed or assigned to tap B, and the highestrange current of the example shown is the tap C. The tap n is the overcurrent drain output.

It should be obvious that only output A can reach the AC level outputdesigned for the lowest current drain of the current sensor range. Whenthe current drain through the primary is in the mid-range of thespecified current sensing, both taps A and B will output voltage levelsexceeding the programmed level, with the voltage of tap A will be wellabove the programmed level. For this reason the level select willconnect the multiplexer input B with the output for feeding power to theregulator 57. Same will apply to the maximum specified current drain,wherein input C will feed through the multiplexer its power to theregulator 57.

In the event of over current drain through the primary coil P the tap nwill feed via the input n its power to the regulator 57 and at the sametime the CPU will alert the controller of the system of the over currentdetection and/or will sound a buzzer of flash an LED (not shown) toalert the user of the system to take corrective measures, or switch offthe load.

Outside the extensions of the current sensing range by the multi tapsolution, the circuits in FIG. 6A and FIG. 7A and their block diagramare identical and they operate the same way through the amplificationcontrol, the power consumption processing and reporting. Shown in FIG.7A are three secondary output taps and depending on the specifiedcurrent sensing range, the operating environment and the loadsselections, any number of taps can be introduced.

For larger current sensors, be it plug-in type, AC outlet type or plugtype as used for heavier load, such as with 50 A, the use of the lowohmic alloys is preferable. For such heavy currents an industrial typeof an AC outlet with current sensor or high power plug with currentsensor or a plug-in current sensor similar to the shown in FIG. 3B butbigger in size to accommodate larger terminals or larger currenttransformer bodies embodying the present invention can be used, insteadof the structured terminal with a resistance element made of low ohmicalloy shown in FIGS. 3B, 4B and 5B.

FIG. 7B shows a block diagram similar to the block diagram of FIG. 6Cwith the exception of the multi current sensing circuits for multi ACpower outlets and/or for AC outlets adaptors and cable assembliesextenders with plurality of AC outlets. The basic circuit of FIG. 7B isidentical with the circuit shown in FIG. 6C, using the structuredresistors of the live AC terminal made of low ohmic alloy RS.

The difference is the adding of n outlets for n loads with each of theterminal socket includes its structured resistor shown as RS-1, RS-2 andRS-n. The expanded CPU 50A provides for each structured resistor RS-1,RS-2 and RS-n to feed it output to an amplifier 51-1, 51-2 and 51-n thatits amplification is controlled by I/O A-1, I/O A-2 and I/O A-nrespectively.

By this circuit arrangement it becomes obvious that a single combineexpanded circuit can be used for a multi AC outlets of a singleelectrical wiring device or for an adaptor with multiple outlets (notshown) or for a cable assembly extender with plurality of AC outlets(not shown), wherein each outlet will provide for sensing its currentdrain and individually report its power consumption.

The reporting of power consumption to a controller directly or via anetwork device, such as a current data receiver that receive RF signalsor optical signals via an optical cable, must include identifying data.The data should include an identification of the load 58 or theappliance or the type of or the family of the appliance.

The data should further include the location of the appliance within thepremise, be it an apartment, or a shop, or a school, or a factory. It ispreferred that the data includes the specific identification of the ACoutlet, or to which current receiver the outlet is connected orreporting to.

As referred to above the use of current transformer to power the circuitmandate the use of a storage capacitor, the capacitor C2 referred toabove for providing sufficient capacity for powering the transceivers,particularly the optical transmitter or the LED that consumes a currentin a range such as 5 mA˜6 mA. Moreover, the capacitor has to storesufficient electric charge to transmit a data when the power is cut, orpreferable to store sufficient charge to respond to at least one inquiryby a controller after the power was cut, or the load was switched off.

Another important factor to minimize the drain of the stored charge inC2 is the length of the reporting time and the data content andstructure. The data loading methods, be it via rotary switches, or viaRF, IR or optical download signals are all disclosed in the referencedpatents, publications and application referred to above. The very shortdata content and structure is disclosed in the referenced applicationSer. No. 13/086,610, all the patents, publications and applications areincorporated herein by reference.

Such short data disclosed in the referenced application Ser. No.13/086,610 structured to five bytes only that include the location, theappliance identification, the power consumed, addressing and otherneeded data for the processing of the reporting and/or the receiving ofan inquiry, such as start bit, end bit, check sum and the nature of thecommand.

Having all these details in a predefined protocol covering the wholerange of appliances, from all the rooms and common zone of a residence,provide the simplicity and standardization for management of theelectricals and the appliances used in residences. The time duration forthe preferred reporting is 20 mSec and the DC current drained for theprocessing and propagating one command (when the power is cut) is 5˜6mA.

The time duration of 20 mSec for the reporting of the current drain orthe power consumption by the current sensor of the present invention iswhen the communication is slow at a rate of 900˜1200 Baud. The DCcurrent drain during the optical transmission is 5˜6 mA, and during RFtransmission is 2˜3 mA. The receiving of an inquiring protocol for thepower consumption or the status of a load will drain an approximate of 1mA, regardless if it is an RF or an optical inquiring protocol. Thismandates a capacitor that can store a charge equivalent to a maximum of6 mA over duration of 60 mSec or 0.06 sec, and a small surface mounted200˜470 micro Farad electrolytic or tantalum capacitor, rated at 6.3V issuffice.

It becomes clear that the use of alloy wires into current transformersand alloy materials for structured power pins, sockets and combinationthereof together with the powering solutions for operating the currentsensors and the power consumption reporting of the present inventionprovide for a new generation of low cost current sensors that waste noor very little power, are simple to manufacture, install and use.

It should be understood, of course, that the foregoing disclosurerelates to only a preferred embodiment of the invention and that it isintended to cover all changes and modifications of the example of theinvention herein chosen for the purpose of the disclosure, whichmodifications do not constitute departures from the spirit and scope ofthe invention.

What is claimed is:
 1. A method for sensing AC current drain through astructured current sensor made of a low ohmic metal alloy by a loadattached to an electrical device selected from a group comprising ACoutlet, AC plug, AC current sensing unit and AC current sensing adaptor,each including said current sensor structured into a portion of at leastone of a terminal selected from a group comprising a power pin, a powersocket, AC terminal and a combination thereof for connecting andconducting the current drawn by said load through said terminal and saidstructured current sensor, said electrical device further comprising aCPU and a current signal amplifier for amplifying a voltage dropdeveloping over said current sensor, said method comprising the stepsof: a. attaching a load to said AC device; b. operating said load; c.feeding the voltage drop developing over said current sensor made of lowohmic metal alloy to said amplifier, d. amplifying said voltage dropsignal; and e. feeding the amplified signal to said CPU for processing.2. The method according to claim 1, wherein said CPU is fed with avoltage reference of said AC power for processing said amplified currentdrain signal coinciding with said reference for deriving the powerconsumed by said load.
 3. The method according to claim 2, wherein saidelectrical device further comprising at least one of an RF transceiverand an optical transceiver for communicating a processed data pertainingto at least one of the current drained and the consumed power via atleast one of in air and through an optical cable respectively.
 4. Themethod according to claim 3, wherein said structured portion is made tofit a size, a shape and a given low ohmic value for developing a voltagedrop commensurate within one of a given current drain values and range.5. The method according to claim 4, wherein said power socket isstructured with a plurality of sockets for use in a multi AC poweroutlet, each said socket includes one said structured portion forconnecting and feeding a voltage drop to an input of one of a pluralityof current signal amplifiers; connecting each output of said pluralityof amplifiers to one port of a plurality of ports included in said CPU,said terminal is connected to an AC power source, said method comprisingthe further steps of: a. connecting each said socket to one load of aplurality of loads; b. operating said loads; c. feeding each voltagedrop pertaining to each load to one of said plurality of amplifiers; d.amplifying said each voltage drop signal; e. feeding the individuallyamplified signals to said CPU; f. processing each individual amplifiedsignal coinciding with said reference for deriving the power consumed byone of each said load individually and a combined power consumed by saidplurality of loads; and g. communicating a processed data pertaining toat least one of the current drained and the consumed power via at leastone of each said socket and the plurality of sockets via at least one ofin air and through an optical cable respectively.
 6. The methodaccording to claim 4, wherein said current sensor is said structuredportion of a combination of said power pin and power socket used in saidAC current sensing adaptor.
 7. The method according to claim 1, whereinsaid structured portion is made to fit a size, a shape and a given lowohmic value for developing a voltage drop commensurate within one of agiven current drain values and range.
 8. The method according to claim7, wherein said electrical device is enclosed in one of a body and acover with a visible color coded ratings selected from a groupcomprising a power consumption range, a power consumption value, acurrent drain range, a current drain value, a power voltage range, apower voltage value, a colored front cover, a colored rear cover, acolored frame, a colored whole body and combinations thereof.
 9. Themethod according to claim 7, wherein said power socket is structuredwith a plurality of sockets for use in a multi AC power outlet, eachsaid socket includes one said structured portion for connecting andfeeding a voltage drop to an input of one of a plurality of currentsignal amplifiers; connecting each output of said plurality ofamplifiers to one port of a plurality of ports included in said CPU,said terminal is connected to an AC power source, said method comprisingthe further steps of: a. connecting each said socket to one load of aplurality of loads; b. operating said loads; c. feeding each voltagedrop pertaining to each load to one of said plurality of amplifiers; d.amplifying said each voltage drop signal; and e. feeding theindividually amplified signals to said CPU for processing.
 10. Themethod according to claim 9, wherein said electrical device is enclosedin one of a body and a cover with a visible color coded ratings selectedfrom a group comprising a power consumption range, a power consumptionvalue, a current drain range, a current drain value, a power voltagerange, a power voltage value, a colored front cover, a colored rearcover, a colored frame, a colored whole body and combinations thereof.11. An apparatus for sensing AC current drain through a structuredcurrent sensor made of a low ohmic metal alloy by a load attached to anelectrical device selected from a group comprising AC outlet, AC plug,AC current sensing unit and AC current sensing adaptor each includingsaid current sensor structured into a portion of at least one of aterminal selected from a group comprising a power pin, a power socket,AC terminal and a combination thereof; said electrical device furthercomprising a CPU and a current signal amplifier for amplifying a voltagedrop developing over said current sensor by the current drawn by saidload and feeding an amplified current signal to said CPU for processing.12. The apparatus according to claim 11, wherein said CPU is fed with avoltage reference of said AC power for processing said amplified currentdrain signal coinciding with said reference for deriving the powerconsumed by said load.
 13. The apparatus according to claim 12, whereinsaid electrical device further comprising at least one of an RFtransceiver and an optical transceiver for communicating a processeddata pertaining to at least one of the current drained and the consumedpower via at least one of in air and through an optical cablerespectively.
 14. The apparatus according to claim 13, wherein saidstructured portion is made to fit a size, a shape and a given low ohmicvalue for developing a voltage drop commensurate within one of a givencurrent drain values and range.
 15. The apparatus according to claim 14,wherein said power socket is structured with a plurality of sockets foruse in a multi AC power outlet, each said socket includes one saidstructured portion for connecting and feeding a voltage drop to an inputof one of a plurality of current signal amplifiers; each output of saidplurality of amplifiers is connected to one port of a plurality of portsincluded in said CPU for feeding the individually amplified currentdrain signal for processing each individual amplified signal coincidingwith said reference for deriving the power consumed by one of each saidload individually and a combined power consumed by said plurality ofloads; a processed data pertaining to at least one of the currentdrained and the consumed power via at least one of each said socket andthe plurality of sockets is communicated via at least one of in air andthrough an optical cable respectively.
 16. The apparatus according toclaim 11, wherein said structured portion is made to fit a size, a shapeand a given low ohmic value for developing a voltage drop commensuratewithin one of a given current drain values and range.
 17. The apparatusaccording to claim 16, wherein said current sensor is said structuredportion of a combination of said power pin and power socket used in saidAC current sensing adaptor.
 18. The apparatus according to claim 16,wherein said electrical device is enclosed in one of a body and a coverwith a visible color coded ratings selected from a group comprising apower consumption range, a power consumption value, a current drainrange, a current drain value, a power voltage range, a power voltagevalue, a colored front cover, a colored rear cover, a colored frame, acolored whole body and combinations thereof.
 19. The apparatus accordingto claim 16, wherein said power socket is structured with a plurality ofsockets for use in a multi AC power outlet, each said socket includesone said structured portion for connecting and feeding a voltage drop toan input of one of a plurality of current signal amplifiers, each outputof said plurality of amplifiers is connected to one port of a pluralityof ports included in said CPU for feeding the individually amplifiedcurrent drain signal for processing.
 20. The apparatus according toclaim 19, wherein said electrical device is enclosed in one of a bodyand a cover with a visible color coded ratings selected from a groupcomprising a power consumption range, a power consumption value, acurrent drain range, a current drain value, a power voltage range, apower voltage value, a colored front cover, a colored rear cover, acolored frame, a colored whole body and combinations thereof.